1. Field of the Invention
The present invention relates to a method for forming the skin of a integral skin foam article. The method includes the steps of forming a skin and subsequently making the skin integral with a core member using a foam produced from polyurethane or the like.
2. Description of the Prior Art
There are several methods for forming the skin of an integral skin foam article. Powder slush molding is one of them. The basic process of slush molding, as illustrated by the flowchart in FIG. 4, involves heating a mold, e.g. to 200.degree. C., filling the preheated mold with a powdered resin, e.g. polyvinyl chloride, permitting the mold to stand for a prescribed period of time, e.g. about 10 seconds, so that the powder in contact with the mold fuses to form a skin, and inverting the mold to recover the excess unfused powder. The mold is heated again and subsequently cooled, and the finished skin is demolded or unmolded, i.e., removed from the mold. The skin thus formed is placed in a foaming mold together with a core member, and a foaming material such as polyurethane is poured into the mold. Upon foaming, an integral skin foam article is obtained. An example of the integral skin foam article thus produced is shown in FIG. 5 in which there is shown a skin 1, core member 2, such as an iron plate, and a polyurethane foam layer 3.
In the conventional skin-forming method, however, the back of the skin 1 is in direct contact with the polyurethane foam 3, which permits the plasticizer in the polyvinyl chloride to migrate to the polyurethane foam. The migration of plasticizer induces degradation, cracking, and discoloration of the skin 1. This problem has been solved in the past by making the skin thicker than 0.8 to 1.0 mm. However, this, in turn, leads to an increase in material costs.
The present invention solves the above-mentioned problems by providing a method whereby plasticizer migration is eliminated or substantially reduced and less raw material is consumed. Accordingly, it is an object of the present invention to provide a method for forming the skin of an integral skin foam article, said skin to be made integral with a core member by the use of a foam in a foaming mold.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.